Composite flywheels such as carbon composite flywheels are desired because they are strong while having a light weight (this is known as having a high specific strength). It is common for the composite flywheels to be connected to a metal shaft for the purpose of putting in or taking out kinetic energy from the flywheel. A common limiting factor for high-performance carbon composite flywheels, or other high-strength fiber composite flywheels, is the connection of the radially expanding (high strained) flywheel rim to the metal shaft, which expands much less (due to its smaller diameter). Typical composite/metal connections do not have sufficient stress/strain capabilities and connections, such as geometrically compliant metal spokes, which lead to dynamic instability. Moreover, connecting flat composite plates, with fibers oriented in a radial direction or near radial direction, form a shaft to rim connection, which produces unmanageable bond/fastener stresses. In addition, using very thick filament wound disks (with a majority of the fibers in the circumferential direction) results in unacceptable radial tensile stresses (across ply stresses) occurring in the hub.
For the reasons stated above and for other reasons stated below, which will become apparent to those skilled in the art upon reading and understanding the present disclosure, there is a need in the art for an effective, efficient and dynamically stable flywheel-to-shaft connection.